278 



PHYSIOGRAPHY. 



Witherite. 



WITHERITE. Di-prismatic Hal-Baryte. 

 MOHS. 



Primary form. Right rhombic prism. M on M= 118 

 30'. 



Secondary form. 



Fig. 482. 



X 



M 



M on M 7 

 h on s 

 h on a 

 h on x 



Anglesack. 



61 30' 



145 30 



126 16 



110 30 



PHILLIPS. 



Cleavage, parallel with M and h imperfect. Fracture 

 uneven. Surface, M horizontally streaked. 



Lustre vitreous, inclining to resinous. The latter more 

 distinct in the fracture. Color white, generally yellowish, 

 approaching to orange-yellow; sometimes passing into va- 

 rious shades of grey. Streak white. Semi-transparent... 

 translucent. 



Brittle. Hardness =3-0 ... 3-5. Sp. gr. =4-301, a 

 white semi-transparent cleavahle variety. 



Compound Varieties. Twin-crystals : axis of revolu- 

 tion perpendicular, face of composition parallel to a face 

 of M. The individuals continued beyond the face of com- 



